Cancer is the major cause of death in the world. In Japan, more than 300,000 people per year die of cancer, and thus the early detection and the treatment of cancer are desired. In most cases, the death of humans due to cancer is caused by metastatic recurrence of cancer. The metastatic recurrence of cancer is caused by fixing and infiltrating tumor cells from a primary lesion through blood vessels or lymph vessels to the blood vessel wall of another organ tissue to form micrometastases. The tumor cell circulating in a human body through blood vessels or lymph vessels as described above is called Circulating Tumor Cell (hereinafter, may be called “CTC”).
In blood, many blood cell components such as red blood cells, white blood cells, and platelets are included, and the number thereof is said to be 3.5×109 pieces to 9×109 pieces in 1 mL of blood. On the contrary, only several numbers of CTCs exist, and thus the blood is needed to be filtered in order to efficiently trap and detect CTCs from the blood cell components. Various studies have been made on such a device. For example, Patent Literature 1 has disclosed a microfluidic devices provided with a polydimethylsiloxane (PDMS) upper member provided with a sample supply ports located at the upper part and the lower part of a nickel substrate having fine through-holes in the nickel substrate and a lower member provided with a sample discharge port.
In addition to the performance to trap and detect CTCs, such a device is required to be easily disassembled in order to take out the detected CTCs from the device. As a device having improved disassembly property, Patent Literature 2 has disclosed a filter unit for biological component separation that solves problems such as labor at the time of disassembly of the filter after use and breakage of the filter, does not cause blood leakage at the circumference of the filter unit, and has an excellent handling property. Patent Literature 3 has disclosed a cell trapping device in which a housing is tightly fixed by joint in order to enable the trapped CTCs to be observed without disassembling the device.